posts tagged with the keyword ‘wood’

2015.01.13

We use tools and machines to extend the reach of the human body. Our expectations do not always live up to our dreams. The Hammer of Futility is a kinetic sculpture created from laser-cut wood that consists of a hammer attempting to hit a nail, and failing, repeatedly. The piece was designed with software, and cut from wood using a laser cutter, then hand assembled, and wired for motion.

2014.12.28

I’ve been looking into press-fit construction techniques for a while now, and I stumbled across this 1917 building set “The Embossing Co Stabuilt Blocks” yesterday. (Nice font, eh?)

It consists of a bunch of wood blocks with round round holes and pegs that hold them together. (I know you’re probably thinking I’m a big fan of LEGO, or maybe TINKERTOY. You’re half right. I’m more interested in the design of these things, and in making my own than I am in building things with them. I’m weird like that.)

I didn’t examine all of the pieces, but one of the longer pegs looked a bit off with the cuts on the end. Maybe many were off like that? It almost gave it a DIY look. The DIY aspect is what I liked about this set. You could (somewhat) easily make one of these yourself if you had access to a basic wood shop.

With digital fabrication techniques you can easily create your own press-fit set. In fact, it’s a thing. For MIT’s “How To Make (almost) Anything” class one of the assignments is press-fit construction.

There’s not a good master index, but you can browse through some of the student work from the past years and stumble across their press-fit assignments. (2014, 2013, 2012, 2011, etc.)

If you don’t get lost in all the documentation of other interesting projects, check out this Fab Academy page about press-fit construction, which has even more links at the bottom.

I’ve got a few projects for 2015 that will rely on press-fit pieces, so if you’ve got any good links, send them my way!

2014.12.19

I’ve been working on a project that involves stacking of laser cut pieces of wood to create blocks. In theory the laser cutter is a precise CNC machine that has an (almost) negligible kerf. (The kerf is the part that gets cut away. With a saw it’s the width of the saw blade, and you need to account for it.)

Typically I’ve been using this 3mm Baltic Birch plywood from Woodcraft, and it’s been pretty darn close to 3mm, at least within 0.1mm. For most projects this is fine. Even at 3.2mm things will fit together, though perhaps a bit snug. You can always sand things a bit to make them fit.

Stacking presents a new problem though, because the extra height adds up and throws everything off. For the last batch of blocks I assembled I wasn’t aware of the issue, even when the pegs wouldn’t fit. I assumed I screwed up the peg slots, so I just sanded the pegs down a bit until they fit. Even then, they were not the right height in the other direction.

After assembly I noticed that the blocks were different heights than the first batch I created! I went back and measured the sheet of wood and it was 3.4mm. I checked a few more and got ranges between 3.0mm and 3.4mm. The image above shows what happens if you use 3mm wood and 3.3mm wood to construct the same block. At just four layers you’re already off by 1.2mm. For small things that can make a huge difference.

So what’s the solution? I can attempt to sand the sheets before cutting, or partially assemble the blocks and sand them to the proper height before the final step. A colleague suggested getting one large sheet of wood assuming the height would be consistent across one piece. I may try all three solutions, but will probably start with the first, and apply the second solution if required.

So yeah, even with digital fabrication, and laser cutters with almost no kerf… Measure twice so you only have to cut once!

2013.11.26

My last attempt at printmaking didn’t turn out as well as I had hoped it would, so I figured it was time to try again. And actually, the main reason I wanted to try again is because I saw the work of Jenie Gao at Milwaukee MakerFest, and after I took over her table so she could take a break, I asked her a few questions about printmaking, and the most important thing I learned is that I should seal the wood. With that small bit of advice, I was ready to try again…

Rather than do the same thing I did last time, I decided to start fresh. I once again used the laser cutter, but this time I didn’t want to use a raster etch, but instead opted for a vector cut to create the plate. (A raster etch works quite well of course, as Bret recently demonstrated, but they are time consuming, and tie up the laser for a long time. Vector cuts are much faster.)

Once I had my pieces cut from 3mm Baltic Birch, I used the piece of wood I cut them from as a guide to glue them down. After the glue dried I sanded it to make the surface nice and smooth. I’m not sure I needed to do this, but sanding always feels like the right thing to do in these situations.

I then coated the piece with polyurethane, sanded it down a bit, and repeated that process two more times. (I’m just doing what is recommended on the can. I don’t know if multiple coats are really needed, but it can’t hurt, right?) I let the whole thing dry for at least 24 hours.

Ready to print! I inked up the plate and slapped down some paper, did a bit of rubbing, and I actually got a decent looking print! One thing I should do next time is create a larger backing piece, as it was hard to hold the plate in place while inking it, and I got a good amount of ink on my fingers and the table. (And yes, that is a mirror I am rolling the ink on. It’s from a 3D printing experiment long ago.)

The final print. There’s a few spots that could use more ink, but as I wasn’t doing a large run, I didn’t use a lot of ink. I also printed on crappy paper and it turned out good. (Supposedly the suggestion of using ‘Rives BFK’ can be ignored. Regular drawing paper can be used instead.)

Ultimately, my plan is to sort of merge the concept of printmaking with letterpress to make a weird combination of the two… but, you know, using a laser cutter and cheap Baltic Birch plywood.

I ended up making a derivative of the Stacking Pi Case and calling it the Raspberry Pi Case (with Camera) because, that’s what it is. I just made the Stacking Case taller and added in some holes to mount the camera.

So if you’ve got a Raspberry Pi and Camera Module, this case might do well for you, since it’ll hold them both. Grab it from Thingiverse!

I’ll get into what I’m doing with this thing in a future post… obviously it will be related to images, time lapses, web stuff, etc.

Oh, and if you’re wondering why the top of the case is purple, it’s due to some crazy experiment I did with dying wood last time I dyed a bunch of t-shirts. And yes, you can totally dye wood.